2004 Honda Civic EX MT rough running

It’s got 210K miles. Just a babe. It idles fine, but intermittently runs rough and shakes at from 10 to 60 mph. Engine light blinks. I had changed the EGR valve 1 year ago, after getting engine light. Now, engine light blinks. I disconnected the EGR electrical connection, and the problem disappeared. Now I have no engine light which is strange because a year ago when I did this, the engine light came on solid when I disconnected the EGR. Anybody have any thoughts?

Does the car have to be in motion to run rough? Does it have to be in gear?

If this is a speed-sensitive thing that only happens in gear, possibly under load, then i would maybe look at other causes than sensors - possibly injectors? After 210K, that could be part of the issue. More info is needed.

Hey, thanks for the response. After many hours of diagnosis on my own, I brought it to a dealership and they tested and found that there was exhaust gas present in the coolant. They did a chemical test and a leakdown test. It cost $139. This makes perfect sense to me now. When the EGR was disconnected, the problem disappeared because it was not recirculating exhaust gases that contained antifreeze. The coolant reservoir had a very slow leak. I had mentioned it to my wife some time ago, but had forgotten about it. So apparently, it’s leaking on the exhaust side. I had done my own compression test, and it was great for a car with 214K miles. I even replaced cyl 4 fuel injector. It actually improved things slightly. The reason I replaced Cyl 4 injector was that that cyl was the first one to misfire (P0304) each time I after I reset the error codes. I had also swapped out an ignition coil.
I’m having the engine replaced with a 60k mile motor. Total cost with new water pump and timing belt $2200. Hopefully it’ll last another 4 years. My wife puts 40k per year on it.
As silly as it might seem, I’m actually disappointed that my 2004 Civic has a head gasket leak. I expect a part like that not to go on a honda that early. My 98 civic is still going strong at 261000.

Honda is nothing special at high mileage except for hype. After 150k miles it is sheer luck what happens or not to ANY make car. I have had two high mileage Civic’s and they did not live up to the hype. Not terrible but do not deserve the reputation they get.

Good luck with the remaining time with it.

The great thing about Civics is that the parts surrounding the engine are also high quality. So you’re not replacing things like you do on american cars. I have a 92 and a 93 Taurus, and I have also owned an 85 ford Escort. The 93 Taurus was a black hole of dying accessories. 1 Alternator, 3 water pumps, 2 radiators, automatic transmission selector switch, engine mount, headlight switch (which melted), ignition switch, rotting suspension parts, rotting body, sheared off tensioner pulley bolt, the cable to open the hood snapped, and more stuff that I can’t remember. The 92 wasn’t as bad, just needed alternator, and radiator. I’ve got 160k on the 93 and 125k on the 92. The 85 escort, before 75K miles needed a new ignition module, new water pump and turn signal module. At 110K needed new clutch and cv joint boots, and head gasket which I did myself. Did the fuel pump, which was mechanical at about 120K. It was leaking transmission fluid where the CV joints went in the transmission. There was a rot hole in the floorboard in front of the gas pedal, and a huge rot hole in the wheel well next to the trunk so that the trunk would get soaked when it rained. I finally got rid of it at 125k when the Brake master cylinder went south. It basically cost more than the car was worth.
With all the work I’ve done on the 93 Taurus, I will hate getting rid of it in a few months. I love that car. It’s like being married. You put so much into it, it’s hard to let it go. I love the ride, the color, the styling, and the roominess, and I bought it the week my youngest daughter was born. I think I might cry when I see it getting towed off into the sunset. I’m getting teary now, I have to stop.

Why replace the engine? A headgasket job for someone who knows what they are doing is not that bad, and you sound like you know whats going on.

I disagree with the other posters on engine life. I have used synthetic oil since the end of break-in on mine and it runs like a champ still with 150K miles. Never seen a mechanic other than me.

You understand that the car has 214K miles on it right? I know honda engines are good, but I’d rather spend 2200 for an engine with 60K on it, and brand new waterpump and timing belt, than spend 800 for a head gasket, and have them open it up to find a cracked or warped head. In my situation, I need the car to last at least another 4 years. I’ve got 3 daughters, all of whom drive. It’s getting cold out, and I don’t want to deal. I’ve done clutches, and a head gasket in the winter. It is not fun, and I just don’t have the time, and I can’t have one of my cars down for several weekends as I bust my ass in the cold garage. No thanks.

Fair enough. Good luck with it.